The sky was "clear" last night, a brief interlude between snow storms. I could see stars, and no obvious clouds, but I wouldn't call it "dark". The measured sky brightness was sqml=18.74. This is about 14 times brighter than a nice dark sky (21.6) in Creede.
I wanted to try out the Hoya Sparkle 6x filter with a shorter focal-length lens, so I set up the Sony A7iii with a Samyang 24mm f/1.8 AF lens. This lens has a convenient feature for astrophotography. There is a button on the lens body that sets the focus to infinity if it is pressed while turning the camera on. This saves time from having to mess around with getting the focus correct.
The image below was obtained using ISO1600 at 15 sec. This was too much exposure for the sky brightness. ISO800 would have been better. A big adjustment to the black level was required to make it look like night. According to Alyn Wallace the Sony A7iii is ISO invariant above ISO640, so that would be an even better setting.
I like the effect of this filter. It will be interesting to do a comparison with the Hoya/Kenko Softon filter under truly dark skies.
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| Sony A7iii + Samyang 24mm f/1.8 AF. 2x binning. |
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| Sirius (Alpha Canis Majoris) and Murzim (Beta Canis Majoris). 12.5° field. |
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| Orion. 22° field. |
As usual, click on an image to get access to the full-size version.
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